High density floppy for the A1200

[Fabie]

It is possible to add a high density floppy drive that works on the A1200 ?
I think it is possible cause the kickstart 3.x have support for High density drives
which PC drives can be modified to work as High density drives on the Amiga?

[pandy71]

Until Paula is not modified to have 500kbps MFM data rate then PC HD FDD can't work as HD FDD in Amiga.

[Mad-Matt]

PC hd can work, but its not in any way relighable and not full capacity with current solution. I tried it many years ago with a tool called HiDensity on Aminet.

[Fabie]

Originally Posted by Mad-Matt

PC hd can work, but its not in any way relighable and not full capacity with current solution. I tried it many years ago with a tool called HiDensity on Aminet.

that archive is a dos driver to format HD disks on escom A1200 drives
but kickstart 3.0+ allows HighDensity drives by default and should works in native format
it seems that same drives works in High density like the sony MPF920 or the chinon FZ-357A
but I can't affirm that...
so
I'm asking which drives can works in Highdensity
or
which drives can be modified

[rkauer]

A few drives can work as HD drives on the Amiga natively: the Chinon FZ357A (originally bundled on A4000 systems) don't require any driver at all to work as Amiga HD drive.

[prowler]

Originally Posted by Fabie

kickstart 3.0+ allows HighDensity drives by default and should works in native format
it seems that same drives works in High density like the sony MPF920 or the chinon FZ-357A
but I can't affirm that...
so
I'm asking which drives can works in Highdensity
or
which drives can be modified

Hi Fabie,

Here is a picture of a Sony MPF920 3½-inch floppy drive which has been modified to work as a High Density Amiga floppy disk drive



This unit behaves as a 1.76MB Amiga High Density floppy disk drive when connected to the internal floppy port of my Commodore KS3.1/WB3.1 A1200!

It is noticeably slower when reading HD-formatted Amiga, MS-DOS and Macintosh disks (I suspect that this is normal, given that the drive is running at half the normal speed during HD R/W operations), but it is working!

The PLCC chip on the right of the picture is what gives the drive Amiga HD compatibility.

And, as my good friend rkauer states above, the Chinon FZ357A will also work without modification.

However, to get either of these drives to mount in an A1200 internally, the fascias have to be removed and the top plate cut or folded back to aviod fouling the case.

[rkauer]

You also have to separate a nice pile of money for the Chinon FZ357A, as they normally are sold for abusive prices in the region of £100 for a drive!

[Fabie]

Originally Posted by prowler

Hi Fabie,

Here is a picture of a Sony MPF920 3½-inch floppy drive which has been modified to work as a High Density Amiga floppy disk drive



This unit behaves as a 1.76MB Amiga High Density floppy disk drive when connected to the internal floppy port of my Commodore KS3.1/WB3.1 A1200!

It is noticeably slower when reading HD-formatted Amiga, MS-DOS and Macintosh disks (I suspect that this is normal, given that the drive is running at half the normal speed during HD R/W operations), but it is working!

The PLCC chip on the right of the picture is what gives the drive Amiga HD compatibility.

And, as my good friend rkauer states above, the Chinon FZ357A will also work without modification.

However, to get either of these drives to mount in an A1200 internally, the fascias have to be removed and the top plate cut or folded back to aviod fouling the case.

good work !!!
where you get info to make that modification?

[Fabie]

thanks for the info guys,

btw,

there are only one floppy drive model on the entire world that works as high density drive on the Amiga...it is the chinon FZ357A ????

I think the idiots of commodore order a special custom made High density drive to chinon to make it exclusive
a unique drive that works at 150rpm instead 300

I was doing some experiments on Winuae with HD drives and
my conlusion is that a high density drive to work on any Amiga requires Kickstart 2.0+ ...... so...that chinon high density drive will not works as high density on the A500 or the A2000

[rkauer]

The FZ357A will work on any Amiga (but the A1000 due size problems) as an internal drive.

[Fabie]

Originally Posted by rkauer

The FZ357A will work on any Amiga (but the A1000 due size problems) as an internal drive.

yes sure
but I think that to work as high density drive needs kickstart 2.0+
because the trackdisk.device on kickstart 1.3 and previous versions do not support high density drives

btw,did you know any other drive that can be modified to work as High density drive on the Amiga?
any other mod or something like that?
schematics?

the problem is I think that the Amiga uses the Shugart interface..which seems a bit different to the IBM one
in the IBM pin 2 is density select....but there is no such pin on the Shugart....so I don't know where pin 2 in a common PC drive should be connected

as a rare experiment...maybe connecting that pin 2 to another pin

[orange]

iirc, aminet had hacks to modify any pc drive so that it works as HD.
it involved placing another magnet on the motor to make it slow down. but the author said it was unreliable.

[Fabie]

Originally Posted by orange

iirc, aminet had hacks to modify any pc drive so that it works as HD.
it involved placing another magnet on the motor to make it slow down. but the author said it was unreliable.

can you add a link to that hack please

btw, ...maybe it is possible to slowdown the motor to 150 rpm using a LM317 transistor connected to the high density switch on the drive
when a high density disk is inserted....enables via the HD switch the LM317 to slowdown the motor
less voltage= less rpm
maybe works
adjusting the LM317 with the motor rpm will be the difficult task
but if the motor uses 12v to make 300 rpm....I calculate we need to adjust the LM317 to 6 or 7 volts to make 150
I wonder if the big motor on the drives uses 12v or 5v

[mech]

Fabie,
the 150rpm HD floppy hack was a result of a mistake in a chip.Since so many chips were already made with this mistake,it was easier for them to modify floppy drives. I think dave haynie spoke about this somewhere.

As for other HD floppies, there was the Amtrade(not sure if it used a 357a):
http://www.amiga-hardware.com/showha...cgi?HARDID=381

There is also a external dell laptop drive that was adopted for amiga as a HD external floppy:

http://www.cucug.org/amiga/amiinfo/reviews/DellDX9.txt

i would be curious to know whats inside the dell drive to make it work on amiga's..i would think it would have soemthing simular to the power computing one.

also high density amiga drives work fine on 500/2000 with 2x+ roms like you mention, never thought to try 1.3 but that was long before highdensity drives exhisted i think..

mike

Originally Posted by Fabie

thanks for the info guys,

btw,

there are only one floppy drive model on the entire world that works as high density drive on the Amiga...it is the chinon FZ357A ????

I think the idiots of commodore order a special custom made High density drive to chinon to make it exclusive
a unique drive that works at 150rpm instead 300

I was doing some experiments on Winuae with HD drives and
my conlusion is that a high density drive to work on any Amiga requires Kickstart 2.0+ ...... so...that chinon high density drive will not works as high density on the A500 or the A2000

[Fabie]

Originally Posted by mech

Fabie,
the 150rpm HD floppy hack was a result of a mistake in a chip.Since so many chips were already made with this mistake,it was easier for them to modify floppy drives. I think dave haynie spoke about this somewhere.

As for other HD floppies, there was the Amtrade(not sure if it used a 357a):
http://www.amiga-hardware.com/showha...cgi?HARDID=381

There is also a external dell laptop drive that was adopted for amiga as a HD external floppy:

http://www.cucug.org/amiga/amiinfo/reviews/DellDX9.txt

i would be curious to know whats inside the dell drive to make it work on amiga's..i would think it would have soemthing simular to the power computing one.

also high density amiga drives work fine on 500/2000 with 2x+ roms like you mention, never thought to try 1.3 but that was long before highdensity drives exhisted i think..

mike

it seems the AMtrade adapter was made to work only with the sony mpf920 and the Teac FD235 drive
the chinon FZ357A does not need any adapter

also I wonder the way to work of that Dell drive...I just read the docs but I don't understand very well what kind of drive is it

[pandy71]

Originally Posted by Fabie

I think the idiots of commodore order a special custom made High density drive to chinon to make it exclusive
a unique drive that works at 150rpm instead 300

Limitation is in PAULA - 125 or 250 kbps for real HD YOU NEED 500kbps.

Modification for each SD/HD FDD (that use BLDC engine) can be made in two ways.

1 - add additional Hall sensor opposite to existing one and connect in parallel to existing one (motor driver think that disk revolving twice fast then it will try to revolve disk half speed)

2 - divide (by 2) reference frequency for motor driver (usually it is something like 3MHz ceramic resonator)

But not each FDD can be modified (not reliable revolutions) in that way - SD drive can be used as HD (Amiga HD is always SD drive even for 1.76MB disks - transfer speed remains the same as in SD)

[prowler]

Originally Posted by Fabie

good work !!!
where you get info to make that modification?

I didn't modify that drive. I bought it from fitzsteve, who told me only that it had been modified to work in a big box Amiga.

I tried it on the internal floppy drive port of my A1200 and it worked as a High Density drive!

Steve told me that it came from here originally:
http://www.efunzine.com/

They must have done the mods, but alas the site is in Polish...

[whitebird]

Hi,

What I understand from this post is that it's not so easy to make an HD PC floppy drive compatible with Amiga.

The problem is that amiga architecture is too much integrated, I mean the floppy drive controller is part of the PAULA chip. It should work if Paula could be clocked twice the original speed with HD floppy. But this cannot be done because all other functions of Paula would also run twice the speed.

In ATARI ST(E) computer the hack was much simplier because the floppy controller is a WD1772 normally clocked at 8MHz for DD floppies. So the only think to do is feed a 16MHz signal and hope the controller will accept this higher frequency.

[Fabie]

Originally Posted by prowler

I didn't modify that drive. I bought it from fitzsteve, who told me only that it had been modified to work in a big box Amiga.

I tried it on the internal floppy drive port of my A1200 and it worked as a High Density drive!

Steve told me that it came from here originally:
http://www.efunzine.com/

They must have done the mods, but alas the site is in Polish...

Ok thanks for the info
now I think that your drive is sony drive with the Amtrade adapter built in
Amtrade:
http://www.amiga-hardware.com/showha...cgi?HARDID=381

it seems that someone in Poland pirated the Amtrade adapter and grab in that PLCC chip....
in other words you have a sony drive + Amtrade adapter

[Fabie]

Originally Posted by pandy71

Limitation is in PAULA - 125 or 250 kbps for real HD YOU NEED 500kbps.

Modification for each SD/HD FDD (that use BLDC engine) can be made in two ways.

1 - add additional Hall sensor opposite to existing one and connect in parallel to existing one (motor driver think that disk revolving twice fast then it will try to revolve disk half speed)

2 - divide (by 2) reference frequency for motor driver (usually it is something like 3MHz ceramic resonator)

But not each FDD can be modified (not reliable revolutions) in that way - SD drive can be used as HD (Amiga HD is always SD drive even for 1.76MB disks - transfer speed remains the same as in SD)

Hi

thanks for your ideas
so...there are hall sensors located in the drives which controls the motor speed?
I was searching for them in 2 pc floppy drives but I can't find any hall sensor
where are generally located????

the only hall sensor I have found are the ones that align the floppy head
can you post a pic please?